I've brewed 2 extract batch now, and both times the OG has been lower than recipes called for. Batch last night called for an OG of 1.052, my reading before pitching yeast was 1.038? Temp. was taken at 74 deg. I will add .001 to my reading, for a total of 1.039. I had no boil overs. I don't boil with my lid on, does that make a difference? I'm lost and looking for help!
Thanks

I'm assuming from your post that you took the reading after adding top-off water to the hot wort allready in your fermenter? It's probable the fluid is stratified because they're simply not mixed together completely. The liquid at the top would then be lighter in gravity than the bottom which will lead to inaccurate measurements. Take a sanitized spoon and give it a good stir, then take a reading--this'll also help with aeration.

I had a simular issue a few years ago. Turned out that I had a defective hydrometer from a cheap kit I had purchased. If you know another homebrewer borrow theirs and check your final gravity with both.